My 2003 Centennial (Ford 100th anniversary Explorer Limited) is equipped with an ATF to air cooler located behind the A/C condenser and in front of the radiator. The stock ATF cooling is adequate for normal driving on moderate days. According to my Scan Gauge II the external cooling loop opens when the internal ATF temperature is 170 deg F. When the ambient temperature is below 80 deg F the ATF temperature stays below 180 deg F even during moderate acceleration. However, I suspect on a hot day here in South Carolina with aggressive driving or mountain driving the ATF temperature will exceed 180 deg F. So after pulling my stock 4.6L SOHC V8 and before installing my modified 4.6L DOHC V8 I want to add a liquid (engine coolant) to ATF cooler that has greater heat transfer capacity than an air to ATF cooler. My 2000 Sport double core radiator on a typical summer day maintains an average temperature of 150 deg F. Since that is greater than ambient temperature the ATF flow should be: 5R55S > liquid-to-ATF cooler > air-to-ATF cooler > 5R55S The photo below from my RatioTek manual shows the 5R55W external cooling loop ports. The ATF cooler flow test in my 2003 Explorer shop manual identifies the direction of flow for each port. The upper port is the 5R55S ATF inlet (return line) from the cooler and the lower port is the 5R55S ATF outlet (supply line) the to the cooler. I purchased an F350 Super Duty ATF cooler for my liquid to ATF cooler. I hope to move the power steering fluid cooler far enough toward the driver side of the cross member to make room for the cooler to be mounted on the passenger side. I'll have to remove the oil filter splash shield.